1. Field of the Invention
The present invention relates to structure detecting and address checking systems for a circular type information transmission system such as loop transmission system, and more particularly to a system for checking the allotted structures of, or the presence or absence of the overlap of, addresses which are assigned to respective transmission control units.
2. Description of the Prior Art
In a prior-art circular type transmission system such as loop transmission system, one of a plurality of transmission control units connected to a loop is used as a master transmission control unit, and this master transmission control unit grasps the transmission situation of the whole loop to perform the controls of sending and reception timings and to take a measure against the fault of the loop. When the master transmission control unit has become faulty, the transmission becomes impossible. However, there has not been a system which does not include the master transmission control unit or a perfect disperse system which does not include a hierarchical control structure corresponding thereto. There has not been a method of automatically checking the overlap of the addresses of the transmission control units in the circular type transmission system or automatically detecting the structure of the system, either.
In a double loop transmission system which accompanies bypassing, a bypass route is constructed in correspondence with the occurrence of a fault in the system, and hence, the structure of the system changes. A prior-art double loop transmission system does not include means to recognize the structure under which the system is presently operating, and this has been problematic in the maintenance of the system.